Aircraft wings commonly comprise deployable control surfaces such as slats, droop noses, airbrakes or ailerons. Slats, for example, are commonly supported on the wing fixed leading edge by two tracks driven by actuators arranged to achieve the correct slat to position for take off and landing of the aircraft. Failure in one of the actuators can lead to a jam of the slat deployment mechanism due to the high back driving torque in the actuator. Such failure can lead to differential track movement causing high tensional stresses in the slat body and high stresses in the slat attachment and the fixed leading edge. Such high stress levels increase the possibility of slat detachment from the aircraft wing.